Current balance circuit to keep dynamic balance between currents in power passages of power connector

ABSTRACT

A current balance circuit includes a first and a second current sensors, an averager, a first and a second control modules, and a first and a second rheostat elements. The first and second current sensors receive a first current and a second current from a power source respectively and convert the first and second currents into a first and a second voltages. The averager receives the first and second voltages and calculates to obtain an average voltage. The first and second control modules receive the first voltage, the second voltage, and the average voltage, to obtain a first and a second control signals, to control current conduction ability of the first and second rheostat elements, to make the first and second currents keep a dynamic balance.

BACKGROUND

1. Technical Field

The present disclosure relates to balance circuits and, particularly, toa current balance circuit.

2. Description of Related Art

In a server, some components need to be connected to a motherboard toreceive currents from the motherboard. A power connector connectedbetween the motherboard and a component has many power passages todisperse the current from the motherboard to each power passage.However, the dispersed currents passing through the power passages areunequal. There is a status that some power passages bear too highcurrent, which leads to a service life of the corresponding componentbeing decreased. While some other power passages bear too low current,which leads to a work efficiency of the corresponding component beingdecreased.

BRIEF DESCRIPTION OF THE DRAWING

The drawing is a circuit diagram of an exemplary embodiment of a currentbalance circuit.

DETAILED DESCRIPTION

Referring the drawing, an exemplary embodiment of a current balancecircuit 1 is connected between a power source 2 and a power connector 3,to balance currents output by the power source 2 to a plurality of powerpassages, such as a first power passage 31 and a second power passage32, of the power connector 3. The current balance circuit 1 includes afirst current sensor 10, a second current sensor 11, a first controlmodule 4, a second control module 5, an averager 16, a first rheostatelement such as a first Metal Oxide Semiconductor Field EffectTransistor (MOSFET) Q1, and a second rheostat element such as a secondMOSFET Q2.

The first control module 4 includes a first subtracter 12, a secondsubtracter 13, and a first delay element 17. The second control module 5includes a third subtracter 14, a fourth subtracter 15, and a seconddelay element 18. The averager 16 is used to calculate an average valueof signals which are input to the average 16, and output the averagevalue. The first and second delay elements 17 and 18 are used to delaythe signals which are input to the first and second delay elements 17and 18, and output the delayed signals. The first and second MOSFETs Q1and Q2 have current conduction ability for the currents passing throughthe first and second MOSFETs Q1 and Q2, and can be controlled by avoltage at gates of the first and second MOSFETs Q1 and Q2. When thevoltage at the gate of each of the first and second MOSFETs Q1 and Q2 isincreased, the current conduction ability of the first and secondMOSFETs Q1 and Q2 is enhanced, the currents passing through the firstand second MOSFETs Q1 and Q2 are increased. When the voltage at the gateof each of the first and second MOSFETs Q1 and Q2 is decreased, thecurrent conduction ability of the first and second MOSFETs Q1 and Q2 isweaken, the currents passing through the first and second MOSFETs Q1 andQ2 are decreased.

The first current sensor 10 is connected to the power source 2 toreceive a first current I1 output by the power source 2, and convert thefirst current I1 into a first voltage V1. The second current sensor 11is connected to the power source 2 to receive a second current I2 outputby the power source 2, and convert the second current I2 into a secondvoltage V2. The averager 16 is connected to the first and second currentsensors 10 and 11 to receive the first and second voltages V1 and V2,and calculate an average voltage V0 of the first and second voltages V1and V2. The averager 16 is also connected to first input terminals ofthe first and third subtracters 12 and 14 to output the average voltageV0 to the first input terminals of the first and third subtracters 12and 14. A second input terminal of the first subtracter 12 is connectedto the first current sensor 10 to receive the first voltage V1. Anoutput terminal of the first subtracter 12 is connected to a first inputterminal of the second subtracter 13. An output terminal of the secondsubtracter 13 is connected to a gate (functioning as a control terminalof the first rheostat element) of the first MOSFET Q1, to output a firstcontrol signal such as a first control voltage to control the currentconduction ability of the first MOSFET Q1.

The first delay element 17 is connected between the output terminal anda second input terminal of the second subtracter 13 to delay the firstcontrol voltage output by the second subtracter 13, and output thedelayed first control voltage to the second input terminal of the secondsubtracter 13. A drain (functioning as a first terminal of the firstrheostat element) of the first MOSFET Q1 is connected to the first powerpassage 31. A source S (functioning as a second terminal of the firstrheostat) of the first MOSFET Q1 is connected to the power source 2 viathe first current sensor 10, to receive the first current I1 output bythe power source 2.

A second input terminal of the third subtracter 14 is connected to thesecond current sensor 11 to receive the second voltage V2. An outputterminal of the third subtracter 14 is connected to a first inputterminal of the fourth subtracter 15. An output terminal of the fourthsubtracter 15 is connected to the gate (functioning as a controlterminal of the second rheostat element) of the second MOSFET Q2, tooutput a second control signal such as a second control voltage tocontrol the current conduction ability of the second MOSFET Q2. Thesecond delay element is connected between the output terminal and asecond input terminal of the fourth subtracter 15, to delay the secondcontrol voltage output by the fourth subtracter 15, and output thedelayed second control signal to the second input terminal of the fourthsubtracter 15. The drain (functioning as a first terminal of the secondrheostat element) of the second MOSFET Q2 is connected to the secondpower passage 32. A source S (functioning as a second terminal of thesecond rheostat) of the second MOSFET Q2 is connected to the powersource 2 via the second current sensor 10 to receive the second currentI2 output by the power source 2.

In the embodiment, the first and second current sensors 10 and 11 canconvert the first and second currents I1 and I2 into the first andsecond voltage V1 and V2, respectively, and at the same time directlyoutput the first and second currents I1 and I2 received from the powersource 2 to the sources S of the first and second MOSFETs Q1 and Q2. Inother embodiments, the sources S of the first and second MOSFETs Q1 andQ2 can be directly connected to the power source 2 to receive thecorresponding first and second currents I1 and I2.

The first subtracter 12 includes an amplifier U1 and resistors R1-R4.The second subtracter 13 includes an amplifier U2 and resistors R5-R8.The third subtracter 14 includes an amplifier U3 and resistors R9-R12.The fourth subtracter 15 includes an amplifier U4 and resistors R13-R16.A non-inverting terminal of the amplifier U1 is connected to a firstterminal of the resistor R1, and is grounded via the resistor R3. Asecond terminal of the resistor R1 functions as the second inputterminal of the first subtracter 12. An inverting terminal of theamplifier U1 is connected to a first terminal of the resistor R2, andconnected to an output terminal (the output terminal of the firstsubtracter 12) of the amplifier U1 via the resistor R4. A secondterminal of the resistor R2 functions as the first input terminal of thefirst subtracter 12. A non-inverting terminal of the amplifier U2 isconnected a first terminal of the resistor R6, and is grounded via theresistor R8. A second terminal of the resistor R6 functions as thesecond input terminal of the second subtracter 13. An inverting terminalof the amplifier U2 is connected to a first terminal of the resistor R5,and connected to an output terminal (the output terminal of the secondsubtracter 13) of the amplifier U2 via the resistor R7. A secondterminal of the resistor R5 functions as the first input terminal of thesecond subtracter 13.

A non-inverting terminal of the amplifier U3 is connected to a firstterminal of the resistor R10, and is grounded via the resistor R12. Asecond terminal of the resistor R10 functions as the second inputterminal of the third subtracter 14. An inverting terminal of theamplifier U3 is connected to the a first terminal of the resistor R9,and connected to an output terminal (the output terminal of the thirdsubtracter 14) of the amplifier U3 via the resistor R11. A secondterminal of the resistor R9 functions as the first input terminal of thethird subtracter 14. A non-inverting terminal of the amplifier U4 isconnected to a first terminal of the resistor R13, and is grounded viathe resistor R15. A second terminal of the resistor R13 functions as thesecond input terminal of the fourth subtracter 15. An inverting terminalof the amplifier U4 is connected to a first terminal of the resistorR14, and connected to an output terminal (the output terminal of thefourth subtracter 15) of the amplifier U4 via the resistor R16. A secondterminal of the resistor R14 functions as the first input terminal ofthe fourth subtracter 15.

In the embodiment, resistances of the resistors R1-R4 are equal.Resistances of the resistors R9-R12 are equal. Resistances of theresistors R5 and R7 are equal. Resistances of the resistors R14 and R16are equal. In other embodiments, the resistances of the resistors R1-R16can be changed according to need. The rheostat elements Q1 and Q2 can beother elements, such as transistors.

When the power source 2 is working, the power source 2 outputs the firstcurrent I1 to the first current sensor 10, and outputs the secondcurrent I2 to the second current sensor 11. The first current sensor 10converts the first current I1 into the first voltage V1, outputs thefirst voltage V1 to the averager 16 and the second input terminal of thefirst subtracter 12, and outputs the first current I1 to the firstMOSFET Q1. The second current sensor 11 converts the second current I2into the second voltage V2, and outputs the second voltage V2 to theaverager 16 and the second input terminal of the third subtracter 14.Wherein I1/I2=V1/V2. The averager 16 calculates the average voltage V0according to the received first and second voltages V1 and V2, namely,V0=(V1+V2)/2. The averager 16 outputs the average voltage V0 to thefirst input terminals of the first and third subtracters 12 and 14. Thefirst subtracter 12 subtracts the average voltage V0 from the firstvoltage V1, to obtain a voltage Vout1=V1−V0. The first subtracter 12outputs the voltage Vout1 to the first input terminal of the secondsubtracter 13. The second subtracter 13 subtracts the voltage Vout1 froma voltage Vk1_1 at the second input terminal of the second subtracter13, to obtain a control voltage Vk1=P1*Vk1_1−(V1−V0), whereP1=R8/(R8+R6). The voltage Vk1_1 is obtained via the first delay element17 delaying the control voltage Vk1 output by the second subtracter 13last time.

Similarly, the third subtracter 14 subtracts the average voltage V0 fromthe second voltage V2, to obtain a voltage Vout2=V2−V0. The thirdsubtracter 14 outputs the voltage Vout2 to the first input terminal ofthe fourth subtracter 15. The fourth subtracter 15 subtracts the voltageVout2 from a voltage Vk2_1 at the second input terminal of the fourthsubtracter 15, to obtain a control voltage Vk2=P2*Vk2_1−(V2−V0), whereP2=R15/(R15+R13). The voltage Vk2_1 is obtained via the second delayelement 18 delaying the control voltage Vk2 output by the fifthsubtracter 15 last time.

When the first current I1 output by the power source 2 is greater thanthe second current I2 output by the power source 2, the first voltage V1output by the first current sensor 10 is greater than the second voltageV2 output by the second current sensor 11, namely, (V1−V0)>0, (V2−V0)<0.The control voltage P1*Vk1_1−(V1−V0) output by the second subtracter 13to the gate of the first MOSFET Q1 is gradually decreased according to(V1−V0)>0. The current conduction ability of the first MOSFET Q1 isweaken. The first current I1 is decreased. The control voltageP2*Vk2_1−(V2−V0) output by the fourth subtracter 15 to the gate of thesecond MOSFET Q2 is gradually increased according to (V2−V0)<0. Thecurrent conduction ability of the second MOSFET Q2 is increased. Thesecond current I2 is increased. Therefore, a difference of currentspassing through the first and second power passages 31 and 32 isdecreased. The first current I1 will be equal to the second current I2.When the first current I1 is equal to the second current I2, namely,I1=I2, the first voltage V1 is equal to the second voltage V2, and theaverage voltage V0 is equal to each of the first and the second voltagesV1 and V2, namely, V0=V1=V2. The second subtracter 13 outputs thecontrol voltage Vk1=P*Vk1_1, the fourth subtracter 15 outputs thecontrol voltage Vk2=P*Vk1_1. Owing to the control voltage Vk1_1 is notequal to the control voltage Vk2_1, the current conduction ability ofthe first and second MOSFETs Q1 and Q2 are different. The first currentI1 becomes unequal to the second current I2. The current balance circuit1 adjusts the first and second currents I1 and I2 again, to make thefirst and second currents I1 and I2 keep a dynamic balance.

When the first current I1 output by the power source 2 is less than thesecond current I2 output by the power source 2, the work process ofbalancing the first current I1 and the second current I2 now is same tothe above-mentioned balancing of the first current I1 and the secondcurrent I2 when the first current I1 is greater than the second currentI2. Therefore, the work process of balancing the first current I1 andthe second current I2 is not described detailed. The current balancecircuit 1 decreases the current difference between the first and secondcurrents I1 and I2 output by the power source 2, to make the firstcurrent I1 substantially equal to the second current I2, thereby keepinga current dynamic balance. In this embodiment, the absoluteness balanceof the first and second currents I1 and I2 is transient.

In other embodiments, the power source 2 can correspond to a pluralityof power connectors. Each of the plurality of power connectorscorresponds to one current balance circuit 1. The current balancecircuit 1 can includes a plurality of current sensors. Each of theplurality of current sensors corresponds to one power passage of thecorresponding power connector.

It is to be understood, however, that even though numerouscharacteristics and advantages of the present disclosure have been setforth in the foregoing description, together with details of thestructure and function of the disclosure, the disclosure is illustrativeonly, and changes may be made in details, especially in matters ofshape, size, and arrangement of parts within the principles of thedisclosure to the full extent indicated by the broad general meaning ofthe terms in which the appended claims are expressed.

What is claimed is:
 1. A current balance circuit to keep a dynamicbalance between first and second currents output by a power source tofirst and second power passages of a power connector, the currentbalance circuit comprising: first and second current sensors connectedto the power source to receive the first and second currentsrespectively, output the first and second currents respectively, andconvert the first and second currents into a first and a second voltagesrespectively; an averager connected to the first and second currentsensors to receive the first and second voltages, and calculate anaverage voltage of the first and second voltages; a first rheostatelement connected to the first current sensor to receive the firstcurrent output by the power source; a second rheostat element connectedto the second current sensor to receive the second current output by thepower source; a first control module connected to the first currentsensor and the averager to receive the first voltage and the averagevoltage, and calculate the first voltage and the average voltage toobtain a first control signal to control a current conduction ability ofthe first rheostat for the first current; and a second control moduleconnected to the second current sensor and the averager to receive thesecond voltage and the average voltage, and calculate the second voltageand the average voltage to obtain a second control signal to control acurrent conduction ability of the second rheostat for the secondcurrent, to make the first and second currents passing through the firstand second power passages keep a current dynamic balance; wherein thefirst control module comprises a first subtracter, a second subtracter,and a first delay element; the second control module comprises a thirdsubtracter, a fourth subtracter, and a second delay element; wherein afirst input terminal of the first subtracter is connected to theaverager to receive the average voltage, a second input terminal of thefirst subtracter is connected to the first current sensor to receive thefirst voltage, an output terminal of the first subtracter is connectedto a first input terminal of the second subtracter, an output terminalof the second subtracter is connected to a control terminal of the firstrheostat element and connected to a second input terminal of the secondsubtracter via the first delay element; wherein a first input terminalof the third subtracter is connected to the averager to receive theaverage voltage, a second input terminal of the third subtracter isconnected to the second current sensor to receive the second voltage, anoutput terminal of the third subtracter is connected to a first inputterminal of the fourth subtracter, a second input terminal of the fourthsubtracter is connected to an output terminal of the fourth subtractervia the second delay element, the output terminal of the fourthsubtracter is also connected to a control terminal of the secondrheostat element; and wherein the first subtracter comprises a firstamplifier and first to fourth resistors, the second subtracter comprisesa second amplifier and fifth to eighth resistors, the third subtractercomprises a third amplifier and ninth to twelfth resistors, the fourthsubtracter comprises a fourth amplifier and thirteenth to sixteenthresistors, a non-inverting terminal of the first amplifier is connectedto a first terminal of the first resistor, and is grounded via the thirdresistor, a second terminal of the first resistor functions as thesecond input terminal of the first subtracter, an inverting terminal ofthe first amplifier is connected to a first terminal of the secondresistor, and connected to an output terminal of the first amplifier viathe fourth resistor, the output terminal of the first amplifierfunctions as the output terminal of the first subtracter, a secondterminal of the second resistor functions as the first input terminal ofthe first subtracter; wherein a non-inverting terminal of the secondamplifier is connected to a first terminal of the sixth resistor, and isgrounded via the eighth resistor, a second terminal of the sixthresistor functions as the second input terminal of the secondsubtracter, an inverting terminal of the second amplifier is connectedto a first terminal of the fifth resistor, and connected to an outputterminal of the second amplifier via the seventh resistor, the outputterminal of the second amplifier functions as the output terminal of thesecond subtracter, a second terminal of the fifth resistor functions asthe first input terminal of the second subtracter; wherein anon-inverting terminal of the third amplifier is connected to a firstterminal of the tenth resistor, and is grounded via the twelfthresistor, a second terminal of the tenth resistor functions as thesecond input terminal of the third subtracter, an inverting terminal ofthe third amplifier is connected to a first terminal of the ninthresistor, and connected to an output terminal of the third amplifier viathe eleventh resistor, an output terminal of the third amplifierfunctions as the output terminal of the third subtracter, a secondterminal of the ninth resistor functions as the first input terminal ofthe third subtracter; wherein a non-inverting terminal of the fourthamplifier is connected to a first terminal of the thirteenth resistor,and is grounded via the fifteenth resistor, a second terminal of thethirteenth resistor functions as the second input terminal of the fourthsubtracter, an inverting terminal of the fourth amplifier is connectedto a first terminal of the fourteenth resistor, and connected to anoutput terminal of the fourth amplifier via the sixteenth resistor, theoutput terminal of the fourth amplifier functions as the output terminalof the fourth subtracter, a second terminal of the fourteenth resistorfunctions as the first input terminal of the fourth subtracter.
 2. Thecurrent balance circuit of claim 1, wherein each of the first and secondrheostat elements further comprises a first terminal and a secondterminal, the first terminal of the first rheostat element is connectedto the first power passage, the second terminal of the first rheostatelement is connected to the first current sensor, the first terminal ofthe second rheostat element is connected to the second power passage,the second terminal of the second rheostat element is connected to thesecond current sensor.
 3. The current balance circuit of claim 2,wherein the first and second rheostat elements are Metal OxideSemiconductor Field Effect Transistors (MOSFETs), a gate of each MOSFETis the control terminal of a corresponding one of the first and secondrheostat elements, a drain of each MOSFET is the first terminal of thecorresponding one of the first and second rheostat elements, a source ofeach MOSFET is the second terminal of the corresponding one of the firstand second rheostat elements.
 4. The current balance circuit of claim 1,wherein each of the first and second rheostat elements further comprisesa first terminal and a second terminal, the first terminal of the firstrheostat element is connected to the first power passage, the secondterminal of the first rheostat element is connected to the power source,the first terminal of the second rheostat element is connected to thesecond power passage, the second terminal of the second rheostat elementis connected to the power source.
 5. The current balance circuit ofclaim 1, wherein resistances of the first to fourth resistors are equal,resistances of the ninth to twelfth resistors are equal, resistances ofthe fifth and seventh resistors are equal, resistances of the fourteenthto sixteenth resistors are equal.